gc: fix up floating point NaN comparisons

Fixes #167.

R=ken2
https://golang.org/cl/155062

src/cmd/5g/cgen.c

@@ -895,8 +895,19 @@ bgen(Node *n, int true, Prog *to)
 	case OLE:
 	case OGE:
 		a = n->op;
-		if(!true)
+		if(!true) {
+			if(isfloat[nl->type->etype]) {
+				// brcom is not valid on floats when NaN is involved.
+				p1 = gbranch(AJMP, T);
+				p2 = gbranch(AJMP, T);
+				patch(p1, pc);
+				bgen(n, 1, p2);
+				patch(gbranch(AJMP, T), to);
+				patch(p2, pc);
+				goto ret;
+			}				
 			a = brcom(a);
+		}
 
 		// make simplest on right
 		if(nl->op == OLITERAL || nl->ullman < nr->ullman) {

src/cmd/6g/cgen.c

@@ -668,7 +668,7 @@ void
 bgen(Node *n, int true, Prog *to)
 {
 	int et, a;
-	Node *nl, *nr, *r;
+	Node *nl, *nr, *l, *r;
 	Node n1, n2, tmp;
 	Prog *p1, *p2;
 
@@ -782,8 +782,19 @@ bgen(Node *n, int true, Prog *to)
 	case OLE:
 	case OGE:
 		a = n->op;
-		if(!true)
+		if(!true) {
+			if(isfloat[nr->type->etype]) {
+				// brcom is not valid on floats when NaN is involved.
+				p1 = gbranch(AJMP, T);
+				p2 = gbranch(AJMP, T);
+				patch(p1, pc);
+				bgen(n, 1, p2);
+				patch(gbranch(AJMP, T), to);
+				patch(p2, pc);
+				goto ret;
+			}				
 			a = brcom(a);
+		}
 
 		// make simplest on right
 		if(nl->op == OLITERAL || nl->ullman < nr->ullman) {
@@ -792,7 +803,7 @@ bgen(Node *n, int true, Prog *to)
 			nl = nr;
 			nr = r;
 		}
-
+		
 		if(isslice(nl->type)) {
 			// only valid to cmp darray to literal nil
 			if((a != OEQ && a != ONE) || nr->op != OLITERAL) {
@@ -831,8 +842,6 @@ bgen(Node *n, int true, Prog *to)
 			break;
 		}
 
-		a = optoas(a, nr->type);
-
 		if(nr->ullman >= UINF) {
 			regalloc(&n1, nr->type, N);
 			cgen(nr, &n1);
@@ -847,12 +856,7 @@ bgen(Node *n, int true, Prog *to)
 			regalloc(&n2, nr->type, &n2);
 			cgen(&tmp, &n2);
 
-			gins(optoas(OCMP, nr->type), &n1, &n2);
-			patch(gbranch(a, nr->type), to);
-
-			regfree(&n1);
-			regfree(&n2);
-			break;
+			goto cmp;
 		}
 
 		regalloc(&n1, nl->type, N);
@@ -860,17 +864,40 @@ bgen(Node *n, int true, Prog *to)
 
 		if(smallintconst(nr)) {
 			gins(optoas(OCMP, nr->type), &n1, nr);
-			patch(gbranch(a, nr->type), to);
+			patch(gbranch(optoas(a, nr->type), nr->type), to);
 			regfree(&n1);
 			break;
 		}
 
 		regalloc(&n2, nr->type, N);
 		cgen(nr, &n2);
+	cmp:
+		// only < and <= work right with NaN; reverse if needed
+		l = &n1;
+		r = &n2;
+		if(isfloat[nl->type->etype] && (a == OGT || a == OGE)) {
+			l = &n2;
+			r = &n1;
+			a = brrev(a);
+		}
 
-		gins(optoas(OCMP, nr->type), &n1, &n2);
-		patch(gbranch(a, nr->type), to);
+		gins(optoas(OCMP, nr->type), l, r);
 
+		if(isfloat[nr->type->etype] && (n->op == OEQ || n->op == ONE)) {
+			if(n->op == OEQ) {
+				// neither NE nor P
+				p1 = gbranch(AJNE, T);
+				p2 = gbranch(AJPS, T);
+				patch(gbranch(AJMP, T), to);
+				patch(p1, pc);
+				patch(p2, pc);
+			} else {
+				// either NE or P
+				patch(gbranch(AJNE, T), to);
+				patch(gbranch(AJPS, T), to);
+			}
+		} else
+			patch(gbranch(optoas(a, nr->type), nr->type), to);
 		regfree(&n1);
 		regfree(&n2);
 		break;

src/cmd/6g/gsubr.c

@@ -1146,8 +1146,6 @@ optoas(int op, Type *t)
 	case CASE(OLT, TUINT16):
 	case CASE(OLT, TUINT32):
 	case CASE(OLT, TUINT64):
-	case CASE(OGT, TFLOAT32):
-	case CASE(OGT, TFLOAT64):
 		a = AJCS;
 		break;
 
@@ -1162,8 +1160,6 @@ optoas(int op, Type *t)
 	case CASE(OLE, TUINT16):
 	case CASE(OLE, TUINT32):
 	case CASE(OLE, TUINT64):
-	case CASE(OGE, TFLOAT32):
-	case CASE(OGE, TFLOAT64):
 		a = AJLS;
 		break;
 

src/cmd/8g/cgen.c

@@ -838,8 +838,19 @@ bgen(Node *n, int true, Prog *to)
 	case OLE:
 	case OGE:
 		a = n->op;
-		if(!true)
+		if(!true) {
+			if(isfloat[nl->type->etype]) {
+				// brcom is not valid on floats when NaN is involved.
+				p1 = gbranch(AJMP, T);
+				p2 = gbranch(AJMP, T);
+				patch(p1, pc);
+				bgen(n, 1, p2);
+				patch(gbranch(AJMP, T), to);
+				patch(p2, pc);
+				break;
+			}				
 			a = brcom(a);
+		}
 
 		// make simplest on right
 		if(nl->op == OLITERAL || nl->ullman < nr->ullman) {
@@ -888,6 +899,14 @@ bgen(Node *n, int true, Prog *to)
 		}
 
 		if(isfloat[nr->type->etype]) {
+			a = brrev(a);	// because the args are stacked
+			if(a == OGE || a == OGT) {
+				// only < and <= work right with NaN; reverse if needed
+				r = nr;
+				nr = nl;
+				nl = r;
+				a = brrev(a);
+			}
 			nodreg(&tmp, nr->type, D_F0);
 			nodreg(&n2, nr->type, D_F0 + 1);
 			nodreg(&ax, types[TUINT16], D_AX);
@@ -915,7 +934,19 @@ bgen(Node *n, int true, Prog *to)
 			}
 			gins(AFSTSW, N, &ax);
 			gins(ASAHF, N, N);
-			patch(gbranch(optoas(brrev(a), nr->type), T), to);
+			if(a == OEQ) {
+				// neither NE nor P
+				p1 = gbranch(AJNE, T);
+				p2 = gbranch(AJPS, T);
+				patch(gbranch(AJMP, T), to);
+				patch(p1, pc);
+				patch(p2, pc);
+			} else if(a == ONE) {
+				// either NE or P
+				patch(gbranch(AJNE, T), to);
+				patch(gbranch(AJPS, T), to);
+			} else
+				patch(gbranch(optoas(a, nr->type), T), to);
 			break;
 		}
 
@@ -941,21 +972,14 @@ bgen(Node *n, int true, Prog *to)
 		a = optoas(a, nr->type);
 
 		if(nr->ullman >= UINF) {
+			tempalloc(&n1, nl->type);
 			tempalloc(&tmp, nr->type);
 			cgen(nr, &tmp);
-
-			tempalloc(&n1, nl->type);
 			cgen(nl, &n1);
-
 			regalloc(&n2, nr->type, N);
 			cgen(&tmp, &n2);
-
-			gins(optoas(OCMP, nr->type), &n1, &n2);
-			patch(gbranch(a, nr->type), to);
-			tempfree(&n1);
 			tempfree(&tmp);
-			regfree(&n2);
-			break;
+			goto cmp;
 		}
 
 		tempalloc(&n1, nl->type);
@@ -974,6 +998,7 @@ bgen(Node *n, int true, Prog *to)
 		gmove(&tmp, &n2);
 		tempfree(&tmp);
 
+cmp:
 		gins(optoas(OCMP, nr->type), &n1, &n2);
 		patch(gbranch(a, nr->type), to);
 		regfree(&n2);

src/cmd/8g/gsubr.c

@@ -260,8 +260,6 @@ optoas(int op, Type *t)
 	case CASE(OLT, TUINT16):
 	case CASE(OLT, TUINT32):
 	case CASE(OLT, TUINT64):
-	case CASE(OGT, TFLOAT32):
-	case CASE(OGT, TFLOAT64):
 		a = AJCS;
 		break;
 
@@ -276,8 +274,6 @@ optoas(int op, Type *t)
 	case CASE(OLE, TUINT16):
 	case CASE(OLE, TUINT32):
 	case CASE(OLE, TUINT64):
-	case CASE(OGE, TFLOAT32):
-	case CASE(OGE, TFLOAT64):
 		a = AJLS;
 		break;
 

test/float_lit.go

@@ -20,8 +20,8 @@ close(da float64, ia, ib int64, pow int) bool
 	db := float64(ia) / float64(ib);
 	db *= pow10(pow);
 
-	if da == 0 {
-		if db == 0 {
+	if da == 0 || db == 0 {
+		if da == 0 && db == 0 {
 			return true;
 		}
 		return false;
@@ -59,8 +59,8 @@ main()
 	if !close(-210e3, -210, 1, 3) { print("-210e3 is ", -210e3, "\n"); }
 
 	if !close(0E-1, 0, 1, 0) { print("0E-1 is ", 0E-1, "\n"); }
-	if !close(+0e23, 0, 1, 23) { print("+0e23 is ", +0e23, "\n"); }
-	if !close(-0e345, 0, 1, 345) { print("-0e345 is ", -0e345, "\n"); }
+	if !close(+0e23, 0, 1, 1) { print("+0e23 is ", +0e23, "\n"); }
+	if !close(-0e345, 0, 1, 1) { print("-0e345 is ", -0e345, "\n"); }
 
 	if !close(0E1, 0, 1, 1) { print("0E1 is ", 0E1, "\n"); }
 	if !close(+10e23, 10, 1, 23) { print("+10e23 is ", +10e23, "\n"); }

test/floatcmp.go

+// $G $F.go && $L $F.$A && ./$A.out
+
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import "math"
+
+type floatTest struct {
+	name string;
+	expr bool;
+	want bool;
+}
+
+var nan float64 = math.NaN();
+var f float64 = 1;
+
+var tests = []floatTest{
+	floatTest{"nan == nan", nan == nan, false},
+	floatTest{"nan != nan", nan != nan, true},
+	floatTest{"nan < nan", nan < nan, false},
+	floatTest{"nan > nan", nan > nan, false},
+	floatTest{"nan <= nan", nan <= nan, false},
+	floatTest{"nan >= nan", nan >= nan, false},
+	floatTest{"f == nan", f == nan, false},
+	floatTest{"f != nan", f != nan, true},
+	floatTest{"f < nan", f < nan, false},
+	floatTest{"f > nan", f > nan, false},
+	floatTest{"f <= nan", f <= nan, false},
+	floatTest{"f >= nan", f >= nan, false},
+	floatTest{"nan == f", nan == f, false},
+	floatTest{"nan != f", nan != f, true},
+	floatTest{"nan < f", nan < f, false},
+	floatTest{"nan > f", nan > f, false},
+	floatTest{"nan <= f", nan <= f, false},
+	floatTest{"nan >= f", nan >= f, false},
+	floatTest{"!(nan == nan)", !(nan == nan), true},
+	floatTest{"!(nan != nan)", !(nan != nan), false},
+	floatTest{"!(nan < nan)", !(nan < nan), true},
+	floatTest{"!(nan > nan)", !(nan > nan), true},
+	floatTest{"!(nan <= nan)", !(nan <= nan), true},
+	floatTest{"!(nan >= nan)", !(nan >= nan), true},
+	floatTest{"!(f == nan)", !(f == nan), true},
+	floatTest{"!(f != nan)", !(f != nan), false},
+	floatTest{"!(f < nan)", !(f < nan), true},
+	floatTest{"!(f > nan)", !(f > nan), true},
+	floatTest{"!(f <= nan)", !(f <= nan), true},
+	floatTest{"!(f >= nan)", !(f >= nan), true},
+	floatTest{"!(nan == f)", !(nan == f), true},
+	floatTest{"!(nan != f)", !(nan != f), false},
+	floatTest{"!(nan < f)", !(nan < f), true},
+	floatTest{"!(nan > f)", !(nan > f), true},
+	floatTest{"!(nan <= f)", !(nan <= f), true},
+	floatTest{"!(nan >= f)", !(nan >= f), true},
+	floatTest{"!!(nan == nan)", !!(nan == nan), false},
+	floatTest{"!!(nan != nan)", !!(nan != nan), true},
+	floatTest{"!!(nan < nan)", !!(nan < nan), false},
+	floatTest{"!!(nan > nan)", !!(nan > nan), false},
+	floatTest{"!!(nan <= nan)", !!(nan <= nan), false},
+	floatTest{"!!(nan >= nan)", !!(nan >= nan), false},
+	floatTest{"!!(f == nan)", !!(f == nan), false},
+	floatTest{"!!(f != nan)", !!(f != nan), true},
+	floatTest{"!!(f < nan)", !!(f < nan), false},
+	floatTest{"!!(f > nan)", !!(f > nan), false},
+	floatTest{"!!(f <= nan)", !!(f <= nan), false},
+	floatTest{"!!(f >= nan)", !!(f >= nan), false},
+	floatTest{"!!(nan == f)", !!(nan == f), false},
+	floatTest{"!!(nan != f)", !!(nan != f), true},
+	floatTest{"!!(nan < f)", !!(nan < f), false},
+	floatTest{"!!(nan > f)", !!(nan > f), false},
+	floatTest{"!!(nan <= f)", !!(nan <= f), false},
+	floatTest{"!!(nan >= f)", !!(nan >= f), false},
+}
+
+func main() {
+	bad := false;
+	for _, t := range tests {
+		if t.expr != t.want {
+			if !bad {
+				bad = true;
+				println("BUG: floatcmp");
+			}
+			println(t.name, "=", t.expr, "want", t.want);
+		}
+	}
+}